This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. SPECIFIC AIMS: Primary objective - dose escalation arm " To determine the MTD of AUY922 as a single agent when administered IV on a once weekly schedule to adult patients with advanced solid tumors, whose disease has progressed despite standard therapy or for whom no standard therapy exists. Primary objective - breast cancer dose expansion arm " At the MTD two further arms will be expanded to assess response (according to a two stage multinomial design) in the following breast cancer patient populations: 1. Patients with HER2 positive non-operable locally advanced or metastatic breast cancer must have: 1. History of trastuzumab resistance, defined as either local or systemic disease progression on treatment with at least 8 weeks of a trastuzumab containing regimen. 2. Received at least 1 but no more than 2 prior anti HER2 based regimens including at least 1 regimen containing trastuzumab. (Patients who develop metastases while receiving adjuvant or neo-adjuvant trastuzumab are eligible) 2. Patients with ER positive non-operable locally advanced or metastatic breast cancer who received standard sequence lines of endocrine therapy and whose disease has progressed on at least one line of endocrine therapy for advanced disease.